5
Modified Sine Wave and Sine Wave Comparison
APPLIANCE POWER CONSUMPTION
MAXX SST
™
Portside Power Inverters are ideal for powering:
• Lights
• TVs and TV/DVD (VCR) combinations units
• Radio receivers/transceivers and stereo systems
• Computers and peripheral equipment
• Refrigerator/freezers
• Small microwave ovens
• Household appliances
• Dry and/or wet/dry vacuums
• Heavy duty power tools & chargers
• Sump pumps, motors and other electric-powered equipment
Most electrical tools, appliances and audio/video equipment have labels that show
the unit’s power consumption in amps, watts, or both. To avoid inverter shutdown and
possible damage to the inverter, avoid exceeding the wattage rating of this unit. To
obtain a rough estimate of the current (in amperes) the power source must deliver
where the power consumption of the tool or device is given in watts AC, simply divide
the power consumption of the load by 110.
Example: If a load is rated at 200 watts AC, the power source must be able to deliver:
200 divided by 110 = 2 amperes.
The inverter has built-in overload protection so that if you do exceed the inverter’s
output capacity continuously, the unit will automatically shut down. Once the
excessive load is removed, the inverter can be restarted and resume normal
operation.
Note:
To restart the inverter, turn it OFF, and then ON again. The ON/OFF Switch is
located on the unit’s Front Panel (see page 2).
The inverter powers resistive loads the easiest; however, larger resistive loads, such
as electric stoves or heaters, could draw more wattage than the inverter can deliver
on a continuous basis.
CAUTIONS
Ensure that total continuous power consumption of all tools and/or
appliances connected to the inverter (and in use) does not exceed the
inverter’s continuous watts rating. Also ensure that start-up wattage
for inductive loads does not exceed peak watts for more than a second.
Appliances such as microwave ovens will normally draw more than
their rated current and could possibly overload the inverter when
operating simultaneously with other appliances. For example: A 600
watt microwave oven draws approximately 940 watts.
110/120V AC
110/120V AC
chargers or solar battery chargers. For most heavy-duty applications, a multiple
battery configuration and the use of deep-cycle batteries is required.
When using multiple batteries, inverters can be operated from one of the vehicle 12
volt batteries, so there’s always one battery with adequate charge to start an engine.
MAXX SST
™
includes a high-surge capability. This is required to start heavy loads,
such as motors and other inductive devices.
PRINCIPLE OF OPERATION
The MAXX SST
™
Portside Power Inverter converts 12 volt DC (direct current) from a
vehicle battery or other 12 volt DC power source to standard 120 volt AC (alternating
current) household power.
It converts power in two stages (see the diagram below). In the first stage, the inverter
raises the 12 volt DC input to 145 volts DC. This inverter uses high-frequency
conversion techniques that replace bulky and heavy transformers found in older
inverters. In the second (output) stage, the inverter converts the 145 volt DC to
110/120 volt AC using multiple banks of metal-oxide semiconductor field-effect
transistors (MOSFETs). The unit’s solid-state circuitry ensures excellent overload
protection and the ability to operate reactive loads such as those found in inductive
motors. In this stage, the inverter functions as a high-power bipolar switch, alternately
applying opposite polarity to the AC outlet HOT and NEUTRAL terminals.
Notes:
Simplified diagram.
Cables, fuse and battery are not included and must be supplied by user.
The Power Inverter Output Waveform
The AC output waveform of the Power Inverter is known as “modified sine wave.” It
is a waveform that has characteristics similar to the sine wave shape of utility power.
This type of waveform is suitable for most AC loads, including linear and switching
power supplies used in electronic equipment, transformers, and motors.
The modified sine wave produced by the Power Inverter has an RMS (root mean
square) voltage of 115 volts, which is the same as standard household power. Most
AC voltmeters (both digital and analog) are sensitive to the average value of the
waveform rather than the RMS value. They are calibrated for RMS voltage under the
assumption that the waveform measured will be a pure sine wave. These meters will
not read the RMS voltage of a modified sine wave correctly. They will read about 20
to 30 volts low when measuring the output of the inverter. For accurate measurement
of the output voltage of this unit, use a true RMS reading voltmeter such as a Fluke
179, Fluke 79 III series, Beckman 4410 or Triplett 4200.
12 VOLT DC
INPUT FROM
BATTERY
AWG
WIRE
AWG
WIRE
AWG
WIRE
+ –
+
–
ANL
FUSE
(external)
TERMINAL
BLOCK
DC TO DC
CONVERTER
INTERNAL WARNINGS &
PROTECTION CIRCUITS
VOLT, AMP METERS
*
OVER TEMP &
VOLT INDICATORS
ON/OFF
SWITCH
145 VDC
MOSFET
BIPOLAR
SWITCH
BANKS
NEUTRAL
HOT
(2, 3 OR 4)
OUTLETS
GROUND
SENSE
FAULT
See Specifications on
page 16 for wire
gauges and fuse
amperages.
4
VEC049_50_51GM_Manual_041906 4/20/06 4:09 PM Page 4
